import Control.Parallel

-- ghc -O2 --make prog_000.hs -threaded -rtsopts

ack 0 n = n + 1
ack m 0 = ack (m - 1) 1
ack m n = ack (m - 1) (ack m (n - 1))

main = do
    a `par` b `par` c `pseq` print (a); print (b); print (c)
    where
        a = ack 1 1
        b = ack 2 2
	c = ack 10 20
